FI60502B - EXHAUST CONTAINER AND EXHAUST - Google Patents

Description

@ FINLAND —FINLAND patent publication — patentskrift 60502 © Kv.lk3lnt.CI? A 61 II 1/03 ® © Patent application — Patentansökning 3 ^ 1 * 7/72 »BShP 8 © Hakemlspilvi— Ansökningsdag 05.12.72 * j * £ XU * © Start date - Giltighetsdag 05.12.72 ® Published public - Bllvlt offentlig 07.06.73 ® Date of posting and date of publication—

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France-France (FR) 71 ^ 3720 (73) Hospal Sodip, 7, avenue Lionel Terray, BP 126, F-69330 Meyzieu, France-France (FR) (72) Alain Granger, Seine et Marne, Andri Sausse, Hauts de Seine,

France-France (FR) (7 * 0 Oy Kolster Ab (5 * 0 Artificial kidney, where the amount of ultrafiltrate can be precisely adjusted -Konstgjord njure, i vilken ultrafiltratmängden kan regleras exakt

The invention relates to an artificial kidney in which the amount of ultrafiltration can be precisely controlled.

Patients with partial or complete renal impairment usually undergo blood dialysis at regular intervals. With each treatment, ultrafiltration through a dialysis membrane must remove precisely defined amounts of water to avoid the formation of hypertones or even edema. The general condition of the patient actually depends crucially on the amount of water removed.

During the blood dialysis treatment, water is removed by adjusting the vacuum of the dialysis solution. However, since the ultrafiltrate is removed with the dialysis solution, it is generally not known during the dialysis that the amount of water actually removed is known.

This amount of water removed depends on a number of factors, including the composition of the blood, which varies during blood dialysis, the accuracy with which the pressures of blood and dialysis solution are known at membrane height, the nature of the membrane and its degree of occlusion; the higher the ultra-filtration rates the membrane allows, the more irregular the amount of water removed. Thus, paradoxically, blood dialysis methods today lead to more random results the better the ultrafiltration properties of the membranes.

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Of course, corrections can be made afterwards, but these must not be done too quickly so as not to disturb the balance of the cellular environment. It would therefore be an advantage to be able to prescribe an ultrafiltration program before the blood dialysis treatment instead of having to carry out post-corrections.

On the other hand, modern membranes can also lead to excessive ultra-filtration rates, especially when handling children. It is then important to be able to reduce the filtration rates to acceptable values and even in some cases to completely prevent ultrafiltration.

It is an object of the present invention to provide a simple and safe means of removing certain amounts of ultrafiltration during a blood dialysis treatment so that the patient is gradually and accurately restored to his proper weight at the end of each treatment.

Another object of the invention is to make better use of the capacities of dialysis wells with a high degree of ultrafiltration.

The invention relates to an artificial kidney in which the amount of ultrafiltrate can be precisely controlled and comprising a blood dialyzer having a first chamber through which the blood to be purified flows and a second chamber for dialysis solution, these chambers being separated by a membrane allowing simultaneous dialysis and ultrafiltration.

The invention is characterized in that the second chamber forms part of a constant volume dialysis solution space closed to the outside air and comprising means for removing a certain part of the dialysis solution from said closed space to keep the volume of dialysis solution constant during treatment and means for detecting this.

For the sake of simplicity, the term "dialysis solution" in the following refers to a solution which is in a closed state, in which case this solution can, of course, contain an increasing amount of ultrafiltrate during the treatment. The proportion of ultrafiltrate generally remains small and is at most a few percent by volume of the amount of dialysis solution.

It is not necessary to completely remove gases (e.g. air) from the enclosed space unless the volume of residual gas prolongs the operating times of the device beyond acceptable limits. Residual gases may be permitted. . . . . 3. . ... 3 a volume of less than 500 cm and preferably less than 200 cm.

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The pressure difference acting on both sides of the blood dialysis membrane is not critical, but depends in particular on the nature of the membrane (permeability, mechanical strength), the amount of ultrafiltration, the degree of occlusion and the difference in osmotic pressures between blood and dialysis fluid. However, this pressure difference is suitably kept within predetermined limits, in which case exceeding these limits indicates a malfunction.

Because blood pressure is generally virtually constant, it is generally sufficient to monitor the pressure in the dialysis fluid space.

This pressure is usually lower than atmospheric pressure (as low as 500 mm Hg, measured in the case of clogged membranes), but this pressure can also be slightly higher than atmospheric pressure (membranes very permeable, ultrafiltration is set to very low values). In the case where blood dialysis is performed without ultrafiltration, the pressure in the closed space simply compensates for the osmotic pressure of the blood relative to the dialysis bath, which pressure is about 30 mm Hg.

The dialysis fluid can be removed from the enclosed space using any suitable device, for example a pump (volumetric or not) or a vacuum generating device. During removal, gases that are either initially dissolved in the dialysis fluid or ultrafiltrate, or that have diffused through the membrane, are removed. The volume of liquid removed must thus be measured after the gases have been removed, for example in a graduated test tube. If desired, the operation of the evacuation device can be controlled by means of a programmed device to which a detector sensitive to volume or degassed liquid flow released from the gases is connected.

The device according to the invention essentially comprises a blood dialyzer, a tank containing dialysis fluid, a circulating pump, a device for removing a controlled amount of fluid and connecting pipes, the internal volume of all these elements being constant. Various auxiliary devices can be connected to this device, such as a thermostat, a dialysis fluid regenerator, for example a charge containing a complex of adsorbent carbon, urease and ammonia absorbent (resin or zirconium phosphate) insulating valve.

The connecting pipes are thick-walled pipes (type "vacuum pipe").

The dialysis fluid reservoir is constructed without deforming it to withstand any vacuum that may be applied to it, so that the walls of this reservoir are thick or reinforced with ribs. This container can be suitably made of, for example, glass, stainless steel or sterilization-resistant polymers.

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During normal dialysis, about 300 liters of dialysis fluid are usually consumed, which requires the use of a spacious device.

However, it is preferred to use compact devices which are beginning to be available and in which various regenerator systems can handle a smaller volume of liquid, whereby the liquid circulates in a closed circuit and waste (e.g. urea, uric acid, creatinine) is retained or disposed of by the above regenerator systems.

It is possible to further reduce the volume of dialysis fluid by allowing urea to accumulate in the blood above normal values: it is known that a person can withstand up to about 1+ g / l of fluid, so it is possible to perform blood dialysis only after loading 3 g / l of urine. A volume of dialysis fluid of the order of Uo 1 (i.e. corresponding to the volume of water contained in the body of a medium-sized patient) thus theoretically allows the urea concentration to be reduced to half, i.e. to 1.5 g / l without regeneration. The amount of urine thus removed corresponds approximately to the amount formed in 3 days.

However, even if such a volume of Uo liter is large enough to purify the blood of other wastes, it is nevertheless suitable to include in the circuit a regenerator of the above-mentioned type in order to increase the efficiency and speed of blood dialysis.

The accompanying schematic diagram, shown by way of example and without any particular scale, shows a particular embodiment of the device according to the invention.

The blood dialyzer 1 is provided with a dialysis membrane 2, by means of which the blood can be ultrafiltered. This membrane separates compartment 3, which is for circulating blood to be purified, from compartment, which is for dialysis fluid. The dialysis fluid is in a closed state 5 »which forms a constant volume closed circuit and which mainly consists of a compartment k, a tank 11 and a circulation pump 6 which circulates the dialysis fluid in the circuit 5 at a rate corresponding to the normal ratios of blood dialysis n.

The tank 11 with a volume of kO liters is made of stainless steel. At the top there is suitably a transparent inspection window 1U of glass. An exhaust pump 8 of the volumetric type sucks liquid from the space 5 through a short immersion pipe and discharges the sucked liquid into a container 9 with a scale. This pressure gauge is provided with minimum and pressure contacts connected to an alarm 13, for example an audible alarm. The cartridge 7 containing activated carbon is placed in a tube which leads back to the blood dialyzer. The temperature controllers 12 maintain the dialysis fluid at 37-38 ° C.

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The device operates as follows: a suitable volume of dialysis fluid prepared and inspected by conventional methods (for example by measuring conductivity) is placed in the enclosed space 5: inspection through the window il * the height of the fluid must be monitored as closely as possible to the end of the immersion tube. By means of the temperature controller 12, the temperature of the dialysis fluid is raised to the desired value and maintained at this value.

The compartment 1 of the blood dialyzer is simultaneously filled with physiological serum and the inlet end of this condition is connected to the patient's artery, the serum is replaced with blood and the outlet end of the condition is connected to the patient's vein.

Dialysis can be started when the dialysis fluid contained in the dialysis circuit has been circulated by the pump 6. The dialysis fluid passes through the activated carbon-containing charge 7, which retains some of the impurities. Ultrafiltration, on the other hand, is carried out by the vacuum generated by the pump 8. The gases dissolved in the blood pass through the membrane 2 and accumulate at the upper end of the container 11.

The pump 8, for example of the peristaltic type, first draws in dialysis fluid or excess air at the upper end of the tank 11. The surface of the dialysis fluid is thus adjusted to a constant height corresponding to the level of the end of the immersion tube connected to the suction side of the pump. The dialysis fluid removed from the tank is collected in a graduated tank 9 · The speed of the pump 8 is adjusted so that the flow rate of the gas released from the gases is the same as the desired ultrafiltration rate. The pressure gauge 10 simply indicates the vacuum prevailing in the circuit 5. If for some reason the value of this vacuum deviates outside the preset limits, an alarm signal is triggered.

Due to the device according to the invention, considerable advantages are achieved. The ultrafiltration rate can be predetermined, and this can also be monitored and, if necessary, easily corrected at any time during dialysis. This dialysis flow has thus been made independent of all the factors on which it has hitherto depended when a certain amount of vacuum is applied to the dialysis fluid. The control of ultrafiltration is a crucial factor in the field of blood dialysis.

In addition, the device according to the invention is very secure. An alarm system connected to a pressure gauge, which in turn is connected to a circuit containing dialysis fluid, immediately signals a possible malfunction. The "low pressure" alarm may indicate too much discharge and thus protect the membrane, while the "high pressure" alarm may indicate a rupture of the membrane or a pipe or, conversely, a blockage of a pipe (due to being compressed). In the event that a disturbance occurs in the blood circulation circuit (hose blocked or broken, patient blood pressure dropped), which Ä 60502 causes a sudden fluctuation in blood pressure in the blood dialyzer, the ultrafiltered fluid transmits this information to the dialysis fluid and triggers an alarm.

Finally, the equipment used can be greatly simplified. In particular, conventionally used accessories such as dialysis bath regenerator and blood dialysis monitors are no longer needed.

The total amount of dialysis fluid required can be prepared in advance and the composition of the dialysis fluid can be examined prior to blood dialysis treatment and, if desired, adjusted to a suitable value. Conductivity measurement thus becomes unnecessary during blood dialysis treatment. In addition, since the bleeding is automatically limited to the amount of dialysis fluid removed, and since, in addition, the height of the dialysis fluid and the color of this fluid can be checked at any time through the inspection window 1U, the colorimeter can be replaced with a visual inspection. The monitoring equipment can be reduced to a pressure gauge 10 with alarms for blood dialysis and to an ultrafiltration tank 9 with a scale for ultrafiltration.

The device according to the invention is particularly suitable for blood dialysis. However, this device can also be easily adapted for ultrafiltration alone. In this case, only the pump 8 has to be connected to a deformable compartment of the blood ultrafiltration membrane on the flow side, after this compartment may have been filled with a liquid (ultrafiltrate or some other liquid), removing an amount of liquid equal to the desired ultrafiltrate.

The following examples illustrate the invention and show the effective application of the device according to the invention in connection with membranes having good ultrafiltration properties.

Example 1 A device schematically shown in the figure is used. Blood dialyzer 1 is of the type described in FR patent 1,597,8I +. The dialyzer is equipped with a blood dialysis membrane of regenerated cellulose, commercially available under the name "Cuprophan". The surface of this membrane is 0.9 m and the membrane allows an ultrafiltration volume of 1.7 milliliters per square meter and mm Hg. The tank 11 is a stainless steel vessel with a volume of 1 + 0 liters and inspection windows 1U at the top. The pressure gauge 10 has high and low pressure alarms.

The circulation pump 6 is of the centrifugal type.

The discharge pump 8 is a volumetric peristaltic type with thick-walled tubes. Tank 9 is a measuring glass with a 5 liter scale. The polypropylene charge 7 contains 500 g of activated carbon. The heating device 12 τ 60502 has a 1 kW electrical resistor and a controller that allows the temperature of the dialysis fluid to be maintained at 38 ° C. These different members are connected to each other by thick-walled silicon-machine elastomer tubes with diameters of 8-1 k mm.

The dialysis fluid circuit 5 is filled from the highest point ...... ..... 3 at the junction in the usual way. Distribute an amount of air of 100 cm to the top 11 of the tank. The dialysis fluid is circulated and its conductivity is measured. The blood dialyzer is connected to a sheep weighing 55 kg and the treatment is started.

The speed of the pump 8 is adjusted to give a degassed amount of ultrafiltrate of 2000 cm / h and it is checked every hour that the amount removed corresponds to the desired amount (adjust the speed of the pump 8 if necessary).

The treatment lasts 10 hours, during which the blood pressure in the dialyzer is maintained at about + 60 mm Hg and the pressure indicated by the pressure gauge 10 at about 100 mm Hg. The urea content of the sheep's blood drops from 2.5 g / l to 1.5 g / l. The amounts of creatine and uric acid in the dialysis fluid are virtually zero after the dialysis fluid has flowed through the activated carbon-containing charge. In addition, 2 liters of liquid are removed from the sheep by ultrafiltration.

Example 2 The same apparatus as in Example 1 is used, but the "Cuprophan" film is replaced by a film made of a copolymer of acrylonitrile and sodium methallyl sulfonate containing 89.5% acrylonitrile. The film has been treated with hot water at 90 ° C and stretched by 180%. This membrane achieves a six times higher amount of ultrafiltration than the previous membrane when all other conditions are the same.

The test is carried out in all respects in the same way as described in connection with Example 1, and in particular the pump 8 is operated at the same speed so as to remove the same volume of ultrafiltrate. The pressure indicated by the pressure gauge 10 is maintained at about + 10 mm Hg.

Example 3 The same apparatus as in Example 2 is used, but without the use of pump 8 except to remove a small amount of gas released during dialysis.

After 10 hours of treatment, the clearance of the blood is as satisfactory as in Example 2, but the sheep has not lost weight.

During operation, the pressure gauge 10 indicates a pressure of approximately + 30 mm Hg.